HONG KONG (Reuters) - Tencent Holdings Ltd has racked up some impressive gains this week - becoming the first Chinese firm to be worth more than $500 billion and surpassing Facebook to be the world's fifth-most valuable company.

HONG KONG (Reuters) - Tencent Holdings Ltd has racked up some impressive gains this week - becoming the first Chinese firm to be worth more than $500 billion and surpassing Facebook to be the world's fifth-most valuable company.